Recovery voltage measurements on XLPE cables

The dielectric response provides information on the physical and chemical structure of a material. For aging processes that affect physically and/or chemically insulating materials, the change in polarization phenomena can be exploited to monitor insulation degradation. One economic way for estimation of the dielectric response are recovery voltage measurements (RVM). Originally, recovery voltage measurements have been used to assess the depolymerization of the paper insulation in transformers. In this paper, it is discussed to what extent RVM can be applied to evaluate the condition of XLPE cables. An adoption of the common RVM test circuit is presented in order to ensure reproducible and meaningful results. Two models have been developed to explain the RVM spectra obtained from unaged cables and a cable containing water trees.